This reminds me of some ways Microsoft used to try catching/dissuading leakers. If someone could find a source for these..

The Xbox 360's dashboard used to have 'aesthetic' rings that actually encoded your serial number, so they could catch leakers

I think I remember hearing somewhere (maybe Dave's Garage) about beta builds of Windows using intricate patterns as wallpapers to trick people into thinking it was also a leak prevention measure.

As the article states, it's an older practice so this maybe goes without saying - canary traps are also useful for tracking the flow of information throughout a population.

A well crafted, bespoke whisper passed into one ear that returns to you from another direction is a very strong signal.